My cache is still rising. Doesn't look like i'm hitting any cap here.. now 1767 files and 77.8MB.
I tested it some more and it looks like its related to the cifs share indeed (its transparent though... MX doesn't know about it. It just sees many new files). The bug seems to work "two-ways". Once cifs is mounted "local files 1" (some specific files) thumbs are missing. If i unmount cifs "local files 2" (other files) are missing. Something seems to collide here. I cannot see any relation between these files though. There are some dupe files present locally (on my phone) that are also on my desktop (cifs share) but i'm sure there are also files that are not.
I will try to setup a scenario with local files only so you can test it better. Will report back.
Galaxy S4 LTE+ I9506:
Snapdragon800 || MSM8974
2.3GHz || 2GB Ram || Adreno330